The present invention relates to a full rotary hook which is disposed in a domestic sewing machine, an industrial sewing machine or the like.
A typical horizontal full rotary hook of the conventional art has a loop taker which is rotated about a rotation axis perpendicular to the axis of a movement path of a needle that is vertically reciprocated; an bobbin case holder which is attached to the inside of the loop taker; a bobbin case which is detachably attached to the inside of the bobbin case holder; and a bobbin around which a bobbin thread is wound and which is then attached to the inside of the bobbin case.
The loop taker has a peripheral wall having a loop seizing beak for seizing a needle thread passed through a needle, and a track groove formed in an inner peripheral portion thereof; a bottom wall connected to one axial end portion of the peripheral wall so as to be perpendicular thereto; and a boss which is integrally formed with the bottom wall so as to be protruded from the bottom wall toward the side opposite to the peripheral wall and is fixed to the lower axis of a sewing machine with being positioned in the circumferential direction. In order to avoid interference with the inserted needle, a notch is formed in the peripheral wall of the loop taker to divide the loop taker in the circumferential direction. The loop seizing beak is formed in one circumferential end portion which is an end portion on the downstream side in the rotation direction of the loop taker.
The bobbin case holder has a peripheral wall having a track projection formed on the outer periphery thereof; a bottom connected to one axial end of the peripheral wall so as to be perpendicular thereto; a flange connected continuously projected in the radial direction outwardly from the other axial end of the peripheral wall; and a stud standing from the center of the bottom to the open end of the inner bobbin case so as to be perpendicular to the bottom. In order to enable the thread passing which will be described later, the track projection is divided along the circumferential direction in the region where the needle is to be inserted. A holder stop recess is formed in the flange. The bobbin case holder is attached to the loop taker under a state where the bottom is placed on the loop taker bottom wall side. The track projection is fitted into the track groove of the loop taker, and the bobbin case holder is rotatably supported with respect to the loop taker. A projection of a holder stop member fixed to the body of the sewing machine is fitted into the holder stop recess, thereby preventing the bobbin case holder from being rotated in accordance with the rotation of the loop taker, in the same direction.
The bobbin case has a peripheral wall on which a bobbin thread tension spring is disposed, and an end wall perpendicularly which is perpendicularly continuous from one axial end of the peripheral wall, and in which a latch mechanism is disposed. Under a state where the bobbin around which the bobbin thread is wound is accommodated, the bobbin case is engagingly attached to the stud of the bobbin case holder by the latch mechanism. The bobbin thread accommodated in the bobbin case is pulled out from the bobbin, passed between the peripheral wall of the bobbin case and the bobbin thread tension spring, and then guided to the upper side through the open end of the bobbin case holder.
The horizontal full rotary hook is configured in the following manner. The loop taker is rotated about the rotation axis, the needle thread supplied by the needle which is reciprocated in synchronization with the rotation of the loop taker is seized by the loop seizing beak, and a loop of the needle thread is passed over the periphery while being expanded along the outer face of the bobbin case holder, thereby performing the thread passing so as to cause the bobbin case holder to pass through the loop of the needle thread. The needle thread is wound around the bobbin thread pulled out from the bobbin. Under this state, the needle thread is pulled up due to an upward motion of a thread take-up lever (not shown), whereby sewing a workpiece on a throat plate is allowed.
Another typical conventional art is an oscillating loop taker which has: a shuttle race body which is fixed to the body of a sewing machine; a shuttle body which is attached to the inside of the shuttle race body; a driver which is swung about a rotation axis perpendicular to the axis of a needle that is vertically reciprocated; a bobbin case which is detachably attached to the inside of the shuttle body; and a bobbin around which a bobbin thread is wound and which is then attached to the inside of the bobbin case.
In the shuttle race body, a track groove which elongates in the circumferential direction is formed in an inner peripheral portion. The shuttle body has: a peripheral wall which elongates along a semi-arc; a bottom wall which is continuous from one axial end portion of the peripheral wall; and a stud which protrudes from the bottom wall toward the other axial end of the peripheral wall. A track projection is fitted into the track groove of the shuttle race body, and the shuttle body is rotatably supported with respect to the shuttle race body.
The driver has the driver body which elongates along a semi-arc, and a boss which is formed integrally with the driver body, and which is fixed to a lower shaft of the sewing machine with being positioned in the circumferential direction. The driver is configured so that the driver body is placed at a position which is shifted by about 180 deg. with respect to the shuttle body in the shuttle race body, and the circumferential ends of the driver body can press the circumferential ends of the peripheral wall of the shuttle body, respectively.
The bobbin case has a peripheral wall on which a bobbin thread tension spring is disposed, and an end wall which is perpendicularly continuous from one axial end of the peripheral wall, and in which a latch mechanism is disposed. Under a state where the bobbin around which the bobbin thread is wound is accommodated, the bobbin case is engaged with the stud of the shuttle body by the latch mechanism so as to be rotatably attached to the shuttle body. The bobbin case is prevented by the shuttle race body from being rotated in accordance with the rotation of the shuttle body. The needle thread accommodated in the bobbin case is pulled out from the bobbin, passed between the peripheral wall of the bobbin case and the bobbin thread tension spring, and then guided to the upper side through the other end side in the axial direction of the shuttle body.
The oscillating loop taker is configured in the following manner. The driver is swung so as to make a half rotation around the rotation axis. The shuttle body is pressed by the driver to be swung between a position where a loop seizing beak is placed upwardly, and that where the loop seizing beak is placed downwardly. The needle thread supplied by the needle which is reciprocated in synchronization with the swing operation of the shuttle body is seized by the loop seizing beak, and a loop of the needle thread is passed over the periphery of the shuttle body while being expanded along the outer face of the shuttle body, thereby causing the loop of the needle thread to be passed over the periphery of the bobbin case to perform the thread passing. The needle thread is wound around the bobbin thread pulled out from the bobbin. Under this state, the needle thread is pulled up due to an upward motion of a thread take-up lever (not shown), whereby sewing a workpiece on a throat plate is allowed.
In the horizontal full rotary hook of the conventional art, the loop of the needle thread is passed over the bobbin case holder by the loop taker on which the loop seizing beak is formed, in such a manner that the loop is passed over the periphery of the bobbin case holder to which the bobbin case is attached. The loop taker for seizing the needle thread and moving the loop of the needle thread is fixed to the lower shaft of the sewing machine, and hence cannot be passed through the loop of the needle thread. The loop of the needle thread is wound around a thread separating portion which is an end portion of the track projection on the upstream side in the rotation direction of the loop taker. The two thread portions of the loop of the needle thread which vertically elongate are separated into the bottom side and open end side of the bobbin case holder, respectively, and passed over the bobbin case holder.
When the lowest end of the loop of the needle thread is passed over the lowest end of the bobbin case holder, a thread portion which upwardly elongates from the loop taker open end side of the loop-seizing-beak-forming-portion where the loop seizing beak is formed, immediately after the thread is seized by the loop seizing beak elongates toward the bottom of the bobbin case holder, and another thread portion which upwardly elongates from the loop taker bottom side of the loop-seizing-beak-forming-portion immediately after the thread is seized by the loop seizing beak elongates toward the open end of the bobbin case holder. Therefore, the loop of the needle thread is passed over the bobbin case holder under a state where the loop crosses above the bobbin case holder. As described above, in the horizontal full rotary hook in which the loop taker for moving the needle thread cannot be passed through the loop of the needle thread, the loop of the needle thread crosses above the bobbin case holder when the loop is passed over the bobbin case holder, and hence the needle thread is easily twisted.
In the oscillating loop taker of the conventional art, the loop of the needle thread is passed over the bobbin case by the shuttle body on which the loop seizing beak is formed. The shuttle body which seizes the needle thread and moves the loop of the needle thread is formed separately from the driver which is fixed to the lower shaft of the sewing machine, and hence can be passed through the loop of the needle thread. The two thread portions of the loop of the needle thread which vertically elongate are separated into the bottom side and open end side of the shuttle body, respectively, and the shuttle body is passed through the loop of the needle thread. In accordance with this, the thread passing is performed so that the bobbin case is passed through the loop of the needle thread.
In the thus configured oscillating loop taker, when the lowest end of the loop of the needle thread is passed over the lowest end of the bobbin case, a thread portion which upwardly elongates from the shuttle body open end side of the loop-seizing-beak-forming-portion where the loop seizing beak is formed, immediately after the thread is seized by the loop seizing beak elongates toward the open end of the shuttle body, and another thread portion which upwardly elongates from the shuttle body bottom side of the loop-seizing-beak-forming-portion immediately after the thread is seized by the loop seizing beak elongates toward the open end of the shuttle body. Therefore, the loop of the needle thread is passed over the shuttle body and the bobbin case with being expanded into a substantially U-like shape without crossing in an Intermediate portion. In the oscillating loop taker in which the shuttle body for moving the needle thread can be passed through the loop of the needle thread as described above, the loop of the needle thread does not cross unlike the above-described horizontal full rotary hook, and hence the needle thread is not twisted.
In the oscillating loop taker which can solve the problem of the horizontal full rotary hook, since the driver which presses the shuttle body is rotated so as to make a half rotation, and the driver must stop two times during an operation of one cycle, and hence it is difficult to improve the operation speed.
Therefore, it is an object of the invention to provide a full rotary hook which enables a needle thread to be wound around a bobbin thread without being twisted, and which can improve the operation speed.
The invention set forth in claim 1 is a full rotary hook comprising:
a shuttle race body which is fixed to a body of a sewing machine and has a track groove formed on an inner peripheral portion of the shuttle race body so as to circumferentially elongate in a circumferential direction thereof;
a shuttle body having a track projection elongating in the circumferential direction and being divided in the circumferential direction, formed on an outer peripheral portion, which track projection is fitted into the track groove to rotatably attach the shuttle body to the shuttle race body, and in which a loop-seizing-beak-forming-portion is formed, the loop-seizing-beak-forming-portion including a loop seizing beak formed at a tip end thereof, for seizing a needle thread supplied by a needle which is vertically reciprocated;
a driver which is continuously rotated in synchronization with a vertical motion of the needle in a predetermined rotation direction, for rotating the shuttle body about an axis of the shuttle body by pressing the shuttle body by rotation of the driver; and
a bobbin case for accommodating bobbin thread, being detachably attached to the shuttle body,
wherein the loop-seizing-beak-forming-portion is formed so as to protrude in a rotation direction of the shuttle body from one circumferential end of the track projection which is placed on a downstream side in the rotation direction of the shuttle body,
in the shuttle race body, a protrusion which protrudes in an axial direction of the shuttle race body so as to face the track groove is formed, and a recess which extends in the circumferential direction is formed on a radial outer side of the protrusion,
the track projection of the shuttle body has an inner peripheral portion and an outer peripheral portion, the outer peripheral portion more protruding toward an open end of the shuttle body than the inner peripheral portion, a protrusion being formed by the outer peripheral portion, and a recess which elongates in the circumferential direction being formed on a radial inner side of the protrusion,
the protrusion of the shuttle race body is fitted into the recess of the track projection of the shuttle body, the protrusion of the shuttle body being fitted into the recess of the shuttle race body, and engaged with the protrusion of the shuttle race body from a radial outer side of the shuttle body, in the outer peripheral portion of the track projection, a projection amount with respect to the inner peripheral portion in regions near circumferential ends is smaller than a projection amount with respect to the inner peripheral portion in a region of a circumferential intermediate portion which is between the regions near the circumferential ends, and the loop seizing beak is formed in a plane including an end face on a shuttle body open end side in the region of the circumferential intermediate portion of the outer peripheral portion of the track projection, and
the loop-seizing-beak-forming portion which more protrudes toward the shuttle body open end than the regions near the circumferential ends of the outer peripheral portion of the track projection is passed through a recess formed in the needle.
According to the invention, the shuttle body having the loop seizing beak for seizing the needle thread is attached to the shuttle race body to be rotatable, pressed by the driver, and continuously rotated in the predetermined rotation direction in synchronization with the vertical motion of the needle. The bobbin case accommodating the bobbin thread is attached to the shuttle body. Under a state where the bobbin thread is pulled out from the bobbin case, the shuttle body is rotated, the needle thread is seized by the loop seizing beak, the loop of the needle thread is expanded along the outer face of the shuttle body, and the loop of the needle thread is passed over the bobbin case so that the bobbin case is passed through the loop of the needle thread, whereby the needle thread is wound around the bobbin thread and a stitch can be formed. The shuttle body which seizes the needle thread and moves the loop of the needle thread while expanding the loop is rotated by the driver which is separately formed. When the loop of the needle thread is to be passed over the bobbin case, therefore, the loop can be passed over the shuttle body. Consequently, the loop of the needle thread can perform the thread passing under a state where the loop is expanded into a substantially U-like shape without crossing in an intermediate portion, and the needle thread is wound around the bobbin thread without forming a twist. Furthermore, the driver is continuously rotated in a predetermined rotation direction, and in accordance with the rotation, the shuttle body is continuously rotated. The driver and the shuttle body do not stop during an operation of one cycle, and hence the full rotary hook can be operated at a high speed.
The track projection has the inner peripheral portion and the outer peripheral portion, and the outer peripheral portion protrudes toward the shuttle body open end with respect to the inner peripheral portion to form the protrusion. In the outer peripheral portion of the track projection, the projection amount with respect to the inner peripheral portion in the regions near the circumferential ends is smaller than the projection amount with respect to the inner peripheral portion in the region of the circumferential intermediate portion which is between the regions near the circumferential ends. The loop-seizing-beak-forming-portion is formed so as to protrude in the rotation direction of the shuttle body from the one circumferential end of the track projection which is placed on the downstream side in the rotation direction of the shuttle body. The loop-seizing-beak-forming-portion functions also as the track projection which is fitted into the track groove. The loop seizing beak formed at the tip end of the loop-seizing-beak-forming-portion is formed in the plane including the end face on the shuttle body open end side in the region of the circumferential intermediate portion of the outer peripheral portion of the track projection.
As described above, the regions near the circumferential ends of the outer peripheral portion of the track projection are formed so as to have a small width and a small projection amount toward the shuttle body open end. According to this configuration, the needle which is vertically moved in the vicinity of the track projection is prevented from interfering with the shuttle body. Although the loop seizing beak is formed in the plane including the end face on the shuttle body open end side in the region of the circumferential intermediate portion of the outer peripheral portion of the track projection, and the loop-seizing-beak-forming-portion protrudes toward the shuttle body open end, the loop-seizing-beak-forming-portion is passed through the recess formed in the needle, and hence does not interfere with the needle.
In the shuttle race body, the protrusion is formed so as to protrude toward the track groove, and the recess is formed on the radial outer""side of the protrusion. In the track projection of the shuttle body, the protrusion is formed by the outer peripheral portion, and the recess is formed on the radial inner side of the protrusion. The protrusion of the shuttle race body is fitted into the recess of the track projection of the shuttle body, and the protrusion of the track projection of the shuttle body is fitted into the recess of the shuttle race body, and engaged with the protrusion of the shuttle race body from the radial outer side. Under this state, the track projection of the shuttle body is fitted into the track groove of the shuttle race body. The track projection of the shuttle body, in which the projection amount in the regions near the circumferential ends of the outer peripheral portion of the track projection is formed so as to be small in order to avoid interference with the needle, is guided by the portion facing the track groove of the shuttle race body, and the shuttle body is rotatable about its axis. Furthermore, the shuttle body is prevented from vibrating in a radial direction during rotation, and can be stably rotated.
The invention set forth in claim 2 is characterized in that, in the configuration of the invention set forth in claim 1, the shuttle body has a spring member which is fixed in a vicinity of a basal end, and
the driver presses a free end of the spring member or a vicinity of the free end.
According to the invention, the driver presses the free end of the spring member of the shuttle body or the vicinity of the free end, the rotation force of the driver is transmitted to the shuttle body via the spring member, and the shuttle body is rotated. As a result, when the driver is continuously rotated, the spring member periodically repeats an elastically deforming operation and an operation of recovering the elastic deformation. This causes the driver and the free end of the spring member or the vicinity of the free end to periodically abut against and separate from each other. When the loop of the needle thread is to be passed over the shuttle body, the loop can be passed through the gap between the driver and the free end of the spring member or the vicinity of the free end during a period when the driver and the free end of the spring member or the vicinity of the free end are separated from each other. When the loop of the needle thread is to perform the thread passing, therefore, the needle thread can be prevented from being pressed between the shuttle body and the driver to be caught thereby, and the loop of the needle thread can smoothly perform the thread passing. Even when the needle thread is accidentally pressed between the shuttle body and the driver, the needle thread elastically deforms the spring member and can be then passed between the driver and the spring member. Therefore, a breakage of the needle thread does not occur.
The invention set forth in claim 3 is characterized in that, in the configuration of the invention set forth in claim 1, a rotation axis of the driver is eccentric with respect to a rotation axis of the shuttle body.
According to the invention, the eccentricity between the rotation axes of the driver and the shuttle body causes the position where the driver presses the shuttle body to be changed in the radial direction of the shuttle body, so that the torque transmitted from the driver to the shuttle body is periodically changed. As a result, at a time when the torque is low, the loop of the needle thread is allowed to pass between the driver and the shuttle body.
The invention set forth in claim 4 is characterized in that, in the configuration of the invention set forth in claim 1, the shuttle body has a peripheral wall on which the track projection is formed, and a needle drop hole is formed in a region of the peripheral wall where the needle is to be inserted.
According to the invention, the shuttle body has the peripheral wall on which the track projection is formed, and the loop of the needle thread seized by the loop seizing beak is moved along the periphery of the shuttle body while being guided and expanded by the peripheral wall, so that the loop of the needle thread can be easily passed over the shuttle body and the bobbin case. The needle drop hole into which the needle is to be inserted is formed in the peripheral wall, thereby preventing the needle and the shuttle body from interfering with each other.